"Israel is indeed planting the seeds of war in the region, I would tell them to stop playing the role of thug in the Middle East," he said.

"Don't test, you Israelis, the determination of Syria. You know that war this time would move to your cities. Come to your senses and choose the road of peace," he added.

The threatening language implied Syria would be willing and able to target Israeli population centers with long-range missiles in a conflict. It was the first time such a threat had been made.

Today Israel's rightwing Foreign Minister Avigdor Lieberman fired back during a speech to businessmen in which he made a direct threat against the Syrian president Bashar al Assad.

"Assad should know that if he attacks, he will lose the war. Neither he nor his family will remain in power," he said.

The two nations have been at loggerheads ever since the Six Day War in June 1967. Israel occupied the Syrian Golan Heights and has remained there ever since. Syria demands the return of its territory as a condition for peace.

Several rounds of U.S.-backed negotiations have come and gone. The most recent talks were mediated by Turkey but were scuppered by Israel's military offensive against Hamas in Gaza at the end of 2008.

Israel has made it clear that Syria must make a strategic turn away from friendship with Iran and its regional allies in exchange for a handover of occupied territory.

Today, Lieberman signaled he thought this most unlikely. "Whoever thinks territorial concessions will disconnect Syria from the axis of evil is mistaken. Syria must be made to understand that it has to relinquish its demand for the Golan Heights," he said.

Israeli Defense Minister Ehud Barak said earlier this week that he feared an absence of a meaningful peace process with Syria would lead to war.

Many voices in Israel's influential military and intelligence community are thought to agree with him, and recommend a genuine peace process with Syria as a priority for the Jewish state.

Ari Shavit, a moderate Israeli commentator, wrote in Thursday's Haaretz newspaper: "To avert a horrendous war not a stone on the road to Damascus should be left unturned."

So far Prime Minister Benjamin Netanyahu seems reluctant to heed this advice and is concentrating instead on the stalled process with the Palestinians. In a speech Wednesday night he said he believed those negotiations would get underway in the next few weeks.

The increase in the rhetorical temperature between Israel and Syria comes during the week the U.S. has announced its intention to restore its ambassador to the Syrian capital. The Bush administration withdrew the ambassador in response to the killing of Lebanese Prime Minister Rafik al Harriri in 2005, a crime for which it held Syria responsible.

Some in Damascus believe the re-establishment of senior U.S. diplomatic representation there could signal a new willingness by the Obama administration to get more involved in the Israeli-Syrian peace track. Its efforts on the Palestinian front have so far proved fruitless.